The present invention relates to a gate forming member for use with an apparatus for serially feeding sheets of paper or the like from the bottom of a generally vertical stack of such sheets.
U.S. Pat. No. 4,991,831, issued to the named inventor of the present application, discloses a sheet feeding apparatus which includes a stationary gate forming member which defines a nip formed between the gate forming member and the upper run of the endless belt which feeds the sheets through the nip. The gate forming member comprises a cylindrical roll, and the roll includes a plurality of annular grooves which are eccentrically disposed with respect to the axis of the roll, and so that the groove is relatively deep along the side facing the stack of sheets, and relatively shallow along the opposite side. The transition between the relatively deep and relatively shallow portions of the grooves is located at the nip, and at a diametrically opposite location.
The roll of the referenced patent includes elastomeric rings disposed in each of the grooves, and the rings are sized so as to lie radially inside of the peripheral surface of the roll about the side facing the stack of sheets, and radially beyond the peripheral surface about the opposite side. This arrangement permits the rings to extend slightly beyond the peripheral surface at the nip. In operation, the gap formed by the nip is adjusted to allow the lowermost sheet of the stack to pass freely therethrough, and so that the sheet above the lowermost sheet frictionally engages the rings at the nip and is thereby retarded. When the lowermost sheet has been moved forwardly a sufficient distance to permit the overlying sheet to contact the endless drive belt, the overlying sheet is then driven forwardly into the nip to form a tight fit, and which in turn causes the sheets to be shingled as they are fed from the stack.
While the apparatus described in the referenced patent operates very reliably and efficiently, the elastomeric rings are subject to wear at the nip and become less effective. As suggested in the referenced patent, the rings may be grasped and rotated circumferentially, to position an unworn portion of each ring at the nip. Alternatively, the rings may be totally replaced.
It is an object of the present invention to provide an improved gate forming member for a sheet feeding apparatus of the described type, and which includes a simple and more efficient system for renewing the rings as they become worn at the nip.